JPH01222209A - Device for measuring object distance for camera - Google Patents

Abstract

PURPOSE:To accomplish focusing on an entire object in a range-finding area by setting the diaphragm value and the focusing distance of a photographic lens so that the nearest and farthest object distances of plural range-finding areas in a photographic image plane respectively become a near point and a far point in the depth of field. CONSTITUTION:The diaphragm value and the focusing distance of the photographic lens are determined so that the nearest and the farthest object distances among plural range-found object distances are respectively equal to the near point and the far point in the depth of the field of the photographic lens. Then, at the time of simultaneously focusing on plural objects A and B which are in different distances, a photographer does not focus on a mean distance as conventional one but photographs by deepening the depth of field. Thus, the photographer can surely focus on the object that he intends. When the plural objects A and B are in nearly same distance, the depth of field is shallowed and photographing such as a portrait whose background is vignetted and which needs knowledge and experience to some extent hitherto can be easily performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to an improvement of a camera object distance measuring device that measures object distances at a plurality of points on a photographic screen.

[Conventional technology]

Conventional distance measuring devices that measure the distance to a subject at multiple points on the shooting screen (so-called multi-point ranging) are designed to focus on the closest subject, or to focus on the average distance of multiple subjects. There are many things that have been done.

That is, for example, JP-A-59-146028,
As shown in Japanese Patent Application Laid-Open No. 62-14015,
One that measures the distance of multiple objects and selects the closest object distance from among the multiple object distance information to focus on, or the center of the distance measurement field of view and/or the adjacent area. There are devices that measure distances and, when multiple distances are measured at the same time, focus on the average distance.

[Problem to be solved by the invention]

Conventional measurement devices that measure subject distances at multiple points on the shooting screen focus on the average distance of multiple subject distances, so there is no possibility that the subject will fall within the depth of field as the photographer intended. In the worst case, there was a possibility that no subject would be in focus.

The present invention makes it possible to always focus on the subject within the shooting screen intended by the photographer, and also to adjust the aperture value so that the subject falls within the depth of field even for subjects at a plurality of different subject distances. The subject distance of the camera such that the focusing distance is set i! The purpose is to provide an i'I measuring device.

[Means to solve the problem]

In order to achieve the above object, a first invention provides a subject distance measuring device for a camera that measures distances to a plurality of points on a photographic screen, and measures the nearest and farthest subject distances among the plurality of subjects whose distances have been measured. The camera is equipped with a means for detecting the object, and a means for determining the aperture value and focusing distance of the photographing lens so that these closest and farthest object distances become the near point and far point of the depth of field, respectively.

The second invention also provides a means for detecting the center or the latest and farthest object distances in the photographing screen among the plurality of measured object distances, and a first photographing mode (normal mode).
As a second shooting mode (depth consideration mode), the nearest and farthest subject distances are focused on the near and far points of the depth of field, respectively. The camera is equipped with a means for determining a comparison value and a focusing distance of the photographing lens so that the photographic lens becomes a point, and a switching means for switching between the first and second photographing modes.

[Effect]

In the configuration according to the first invention described above, the aperture value of the photographing lens is adjusted so that the nearest and farthest subject distances of the plurality of distance measurement areas in the photographing screen become the near point and far point of the depth of field, respectively. The focal length is set and the entire subject within the distance measurement area is brought into focus.

Further, in the configuration according to the second invention, in the first shooting mode, that is, the normal mode, for example, a subject distance at the center of the shooting screen is detected among a plurality of subject distances measured within the shooting screen, and the subject is If the distance is shorter than a predetermined constant distance, the camera will focus on the subject distance at the center of the photographic screen, and if it is farther, it will focus on the most recent subject distance within the photographic screen. In addition, in the second shooting mode, that is, depth consideration mode, the shooting lens adjusts the nearest and farthest subject distances of multiple distance measurement areas in the shooting screen to become the near and far points of the depth of field, respectively. The aperture value and focusing distance are set, and the entire subject within the distance measurement area is brought into focus. By selectively using the normal mode and the depth consideration mode depending on the subject, it is possible to reliably focus on the subject intended by the photographer.

〔Example〕

FIG. 1 shows a schematic configuration of a subject distance n1 fixing device for a camera according to the present invention.

The basic configuration of this device is a light projector and a light receiver, which are placed on the front of the camera body with a predetermined baseline length apart.

In FIG. 1, a near-infrared light emitting diode, a flash discharge tube, etc. are used as the light source section 1, and a slit plate 2 and a floodlight lens 3 are arranged in front of the light source section 1, and a cylindrical concave lens is installed as necessary. 4 is placed. Further, the slit plate 2 is arranged on the focal plane of the light projecting lens 3. There are multiple slit plates 2 in the direction perpendicular to the base line length (three in this case).
It has wide slit holes 2A, 2B, and 2C, and the area other than the slit holes is designed to block light.

Furthermore, in order to reduce blurring of the off-axis reflected slit image due to aberrations of the projecting lens 3, the slit plate 2 is curved, for example, concavely, in a direction that corrects the blurring.

A light beam projected from a light source 1 passes through a slit plate 2 and is divided into three beams having a width perpendicular to the base line length, and this slit light beam passes through a projection lens 3 and is projected toward the subject. 5A, 5B, and 5C show the slit images.

Here, the dotted line portions of the slit images 5A, 5B, and 5C are indicated by the dotted lines because when the photographing lens of the camera is a bifocal lens or a zoom lens, the proportion of the distance measurement area on the photographic screen becomes smaller when photographing with a wide-angle lens. This shows a state in which the width of the slit beam is widened to compensate. The width of this slit light beam can be increased by placing the cylindrical concave lens 4 in front of the projection lens 3 so that the axis of rotation of the cylindrical surface is perpendicular to the wide direction of the slit hole.

The reflected lights 5A', 5B', and 5C' of the pickpocket beam projected toward the subject pass through the light receiving lens 7 and the aberration correction concave lens 8, and are sent to the light receiving element 9 such as the position sensor (PSD). It is incident. Here, if a cylindrical concave lens 4 is inserted in front of the light emitting lens 3 in order to expand the width of the slit light beam, a cylindrical concave lens 6 is also inserted in front of the light receiving lens 7 to correct the expanded portion. Place the cylindrical surface so that its axis of rotation is perpendicular to the wide direction of the reflected light.

FIG. 2 shows the light-receiving element 9 and the reflected image incident on the light-receiving element 9.

In the figure, reflected images 5A' and 5B' are shown in the shaded areas.

Light receiving elements 9A and '9B correspond to 5C', respectively.

9C is placed. These light receiving elements 9A and 9B.

9C is divided into n pieces in the wide direction of the reflected images 5A', 5B', and 5C', and each of the light receiving strings 9Ai to 9A
n, 9 B1-9 Bn, 9 C1-9
Cn independently outputs a signal indicating its light receiving position.

Here, the configuration of the light receiving element (position sensor) will be explained with reference to FIG.

In the figure, a resistor 10 is formed on the surface of the light-receiving element, and when light is incident on the resistor 10, a current I! flows.

A' B Here, if the length between the electrodes 11A and 11B is L1, the resistance is R, the length L between the electrode 11A and the light incident position is χ, and the resistance is Rχ, then at a certain position on the light receiving element The relationship between the output current (1)9 and Is when light is incident is as follows.

1-10-(RL-R,)/RL.

IBWIO11Rχ°/RL (1 o-1a + I B) Here, if the length and resistance value are proportional, 1, -10 ・ (L-χ)/L 1B-10-χ/L , °, IA/ IB-(L-χ)/χ Therefore, from the above formula, the output current! 6 and! By determining the ratio of 8, the incident position of the light on the light receiving element can be determined regardless of the incident energy.

Next, the principle of the device of the present invention will be explained. Figures 4 and 5
The figure shows the functional configuration of this device. In the figure, the slit-shaped light beams projected from the slit holes 2A, 2B, and 2C pass through the projection lens 3 and are reflected by the objects 20, 21, and 22, and the reflected light is Passing through the light receiving lens 7, the light receiving element 9A
, 9B, and 9C. Here the subject 20.21
．． 22 is in the autofocus (AF) measurable distance range (range from the closest distance to infinity where the distance to the subject can be measured), the slit holes 2A, 2B.

The reflected light of the slit-shaped light beam projected from 2C is incident on the corresponding light receiving elements 9A, 9B, and 9C, respectively. Since the slit image moves on the light-receiving element according to the distance to the subject, the subject distance can be measured every 1lllj distance based on the principle of triangulation. After this measurement, an instruction is issued to, for example, focus on the closest subject. The number of slits and the spacing between them are designed so that when the subject is within the AF distance measurable distance range, the reflected image from the subject will not enter any light receiving element other than the corresponding light receiving element. In addition, the closest distance that can be measured by AF is, for example,
It is set equal to the closest distance of the photographing lens.

FIG. 4 shows a case where all objects are within the AF distance measurable distance range, and FIG. 5 shows a case where some objects are on the shorter distance side □ than the AF distance measurable distance range. In FIG. 5, the slit-shaped light beam projected from the slit hole 2B passes through the projecting lens 3 and hits the subject 21 located at a shorter distance than the AF measurable distance range, and the reflected light passes through the light receiving lens 7 and hits the light receiving element. is incident on the

Here, the reflected light of the luminous flux from the slit hole 2B should originally be incident on the corresponding light receiving element 9B, but since the subject 21 is on the shorter distance side than the AF rangefinder possible distance range, the light receiving element 9B The light does not enter into the adjacent light receiving element 9C. In this case, the output of the light-receiving probe 9 will be larger than normal, so if the output exceeds a certain value, it is assumed that the subject is closer than the shortest shooting distance of the photographing lens, and for example, if the subject is in a different area. It performs processing such as adjusting the focus or issuing a short-range warning.

FIG. 6 shows the relationship between the amount of light received on the light receiving element and the distance. As shown in the figure, the amount of light received on the light receiving element 25 increases as the distance increases. As mentioned above, since the subject is closer than the AF ml distance range, the light receiving element 9
Even if the reflected light that should be incident on B is incident on the light receiving element 9C, the output of the light receiving element 9C will be larger than normal, so
When the value exceeds a certain value, it is determined that the subject is closer than the shortest photographing distance of the photographic lens, and processing can be performed.

Next, the block configuration of this device is shown in FIG. In the figure, when a release switch (SW) 51 is turned on, a trigger circuit 52 is activated, and a microcomputer 53 (center of the shooting screen,
Alternatively, a signal is sent from the means for detecting the nearest and farthest subject distances and the means for determining the aperture value and focusing distance to the light emitting element drive circuit 54 to cause the light emitting element of the light source section 1 to emit light. A light beam projected from a light source section 1 is divided into a plurality of light beams by a slit 2, and projected onto a subject (not shown) via a light projection lens 3. This projected light flux is reflected by the subject, and the light receiving elements 55-1 to 55-n
(the same as the above-mentioned light receiving cable 9). When reflected light is incident on the light receiving cables 55-1 to 55-n, currents IA and IB flow through their output terminals in accordance with the incident position of the light, and the distance calculation circuit 56- is activated at the timing of light emission from the light source section 1. 1
~56-n, each I/IB (subject distance) is calculated and output. These outputs 1/
I8 corresponds to each of the light receiving elements 55-1 to 55-n.
Each of the signals is A/D converted by D conversion circuits 57-1 to 57-n.

Each value of 1/I8 A/D-converted by the A/D conversion circuits 57-1 to 57-n is determined by the light receiving element 55-1.
Each memory circuit 58-1 to 58-n corresponding to 55-n
is memorized.

Next, the calculation processing of the microcomputer 53 will be explained. When the mode changeover switch (SW) 59 is set to the normal mode (first shooting mode), the microcomputer 53 inputs distance information of the distance measurement area at the center of the shooting screen (temporarily the data value of the 58-mth memory circuit). ) is the multiplexer 60
, and determines whether the subject distance data is closer than a predetermined distance value, and if it is close, sends a signal to the lens drive motor drive circuit 61 to focus on the subject in the center of the shooting screen, and turns the lens. drive. If it is far away, the multiplexer 60
Memory circuit 58-1 stores object distance data for one distance area.
- 58-n, the closest object distance data is detected, and a signal is sent to the lens drive motor drive circuit 61 to drive the photographing lens so as to focus on that distance.

Next, a case will be described in which the mode changeover switch (SW) 59 is set to the depth consideration mode (second photography mode). First, the microcomputer 53 uses the f information reading circuit 6
2 reads the focal length (f) of the photographic lens, and then the multiplexer 60 sequentially reads the subject distance data for each distance measurement area from the memory circuits 58-1 to 58-n, and displays the recent subject distance and the farthest subject distance. Detect distance objects.

Next, read the focusing distance M (Do) and aperture value (F No.) above so that the most recent subject distance and the farthest detected subject distance become the near and far points of the depth of field, respectively. Calculated from the focal length (f). Then, the signal of this calculated data is sent to the lens drive motor drive circuit 61,
Drive the lens.

The above processing method will be explained in detail using the flowchart of FIG.

First, the operation starts with the start of step 101,
Reset each memory etc. Next, in step 102, the subject distance for each distance measurement area is calculated, and in step 103, the mode set by the photographer is determined. If the mode is normal mode, the process moves to step 104; if the mode is depth consideration, the process moves to step 110. do.

In the case of normal mode, in step 104, the object distance data Lm of the distance measurement area at the center of the shooting screen is compared with a predetermined constant distance Lc, and if Lm<Lc, the object pressure to be focused is determined in step 105. @Ls is set to become Ls-Lm, the photographing lens is driven in step 106, and the process is ended in step 107. Also, Lm≧L
If c, the closest distance data L win is detected from among the subject distance data of all the distance measurement areas in step 108, the distance data is set to be Ls-Lsin in step 109, and the photographing lens is driven in step 106. and step 1
The process ends at 07.

Next, in the case of the depth consideration mode, in step 110, the focal length of the photographing lens is i! +1 Read (f), step 1
11, the closest distance data L s+in and the farthest distance data L from the subject distance data of each a-1 distance area
Detect sax. Next, in step 112, the nearest distance data L m1n and the farthest distance data L wa
When x is the near point and far point of the depth of field, the distance Do to be in focus and the aperture value FNQ are calculated from the following equations.

La1n ・(1+N*t: ・Lsax)Do-
□ 1 10 N = ε・L −1n f 2・(Lmax −Lsln) FNα san N −e * (Lmax + Latin
) Here, N is the diagonal length of the photographic screen, ε is the diameter of the permissible circle of confusion, and f is the focal length of the photographic lens.

Next, in step 113, the subject distance Ls to be focused is set to L
s-Do is set, the photographing lens is driven in step 106, and the process is ended in step 107.

Next, the L s1n detection subroutine of step 108 will be explained using the ninth @. Step 108-
In step 108-2, the subject distance data L1 of the i-th distance measurement area is compared with the closest subject distance data L1n. Here, Ll<Lsl
If n, in step 108-s, the data Li is replaced with the nearest object distance data Lm1n, and LL≧Ls
If it is 1n, do not process anything and proceed to step 1.
08-4 and increment i by 1. Step 108-
In step 5, it is determined whether the above processing has been completed for all distance measurement areas, and if it has not been completed, the process returns to step 108-2 and the processing is repeated. If the process has been completed, the object distance data L m1n contains the closest distance data among all the measured distance data, and the process returns to the main routine in step 108-6.

Next, the subroutine for detecting Lsax and Llln in step 111 will be explained using FIG.
In step 111-1, i is initialized to i-1, and in step 111-2, the subject distance data Li of the i-th distance measurement area and the farthest subject distance data Lsax are compared, and if Li>Lsax, For example, in step 111-3, the data Li is replaced with the farthest object distance data L wax, and the process moves to step 111-6. If Li≦L
wax, the process moves to step 111-4, compares the closest subject distance data LsIn and Li, and determines that Li<
If L sln, the data Li is replaced with the nearest object distance data L mln in step 111-s. If Li≧L sag, proceed to step 111-a without processing anything, and in step 111-a
is incremented by 1, and in step 111-7 it is determined whether the above processing has been completed for all distance measurement areas. If not completed, return to step 111-2 and repeat the process,
If the shooting has been completed, the object distance data L■aX contains the distance data that is the farthest among all the measured distance data, and the object distance data Lm1n contains the distance data that is the closest among all the measured distance data. , step 111-, the process returns to the main routine.

Next, operations in various states of the subject within the photographic screen will be explained with reference to FIGS. 11 to 13 in a mode that takes depth into consideration among the above-described processing methods.

In these figures, 30 indicates a photographing screen, and 31 indicates a distance measurement area. FIG. 11 shows a case where the AP1 distance area 31 in the shooting screen 30 is set to the same subject A, and FIG. This is a case where the image is adjusted to B (here, both are people). In either case, the nearest and farthest distances of the subject distance, n1 distance, are taken as the near and far points of the depth of field, so the background does not fall within the subject distance, and the background is blurred, so-called portrait photography. becomes possible.

Figure 13 shows subject A (person) at a relatively close distance,
ilN distance area 31 to subject B (house) behind it.
This is the case when both are combined. Both subjects A and B are photographed with the aperture set so that they are within the depth of field and in focus. In addition, in the same way, three distance measurement areas 3
1 for subject A, respectively.

By aligning B with the mountains in the background, everything from the person to the mountains in the background come within the same depth of field, making it possible to take a photograph in a focused state.

〔Effect of the invention〕

As described above, according to the invention described in claim 1, in the object distance measuring device that measures a plurality of points on the photographing screen, among the plurality of object distances ag1 distances, the nearest and farthest object distances are respectively determined by the photographing lens. The aperture value and focusing distance of the photographic lens are determined so that the near point and far point of the depth of field are equal. Therefore, when you want to focus on multiple subjects at different distances at the same time, instead of focusing on the average distance as in the conventional method, the depth of field is deepened, so you can be sure that the subject is the one you want. can be focused on. Additionally, when multiple subjects are at similar distances, the depth of field becomes shallow, making it easier to take portrait-like shots with blurred backgrounds, which previously required a certain amount of knowledge and experience. can.

Further, according to the invention as set forth in claim 2, a shooting mode for focusing on the center of the shooting screen or a recent subject distance is provided separately from the shooting mode as set forth in claim 1, and these modes can be selected. Therefore, the photographer can easily switch between these shooting modes and enjoy taking photos in different modes.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the basic configuration of an embodiment of the subject pressure 111171P3 fixing device for the camera of the present invention;
The figure shows a light-receiving element in the device and a reflected image incident on the device, FIG. 3 is a configuration diagram of the light-receiving element, and FIGS. 4 and 5 are plan views for explaining the principle of the device of the present invention. 6th
FIG. 7 is a block diagram showing an example of a specific circuit configuration of the device of the present invention, and FIGS. 8, 9, and 10 are control means of the device of the present invention. 11, 12, and 13 are flowcharts showing one example of the flowchart, and FIGS. 11, 12, and 13 are photographing screen configuration diagrams for explaining the present invention in detail. 30... Shooting screen, 31... Δp1 distance area, 53
...Microcomputer, 55-1 to 55-n...Light receiving cable,
56-1 to 56-n...Distance calculation circuit, 59...Mode changeover switch, 61...Lens drive motor drive circuit. Patent applicant Minolta Camera Co., Ltd. Representative
Person Patent Attorney Etsu Kotani Purpose
Chief Patent Attorney 1) Masayuki
Patent Attorney Yasuo Itaya Figure 3, Figure 9 Figure 10

Claims (1)

[Scope of Claims] 1. In a camera subject distance measuring device that measures a plurality of points on a photographic screen, means for detecting the nearest and farthest subject distances among a plurality of subjects whose distances have been measured; A subject distance measuring device for a camera, characterized by comprising means for determining the aperture value and focusing distance of a photographing lens so that the nearest and farthest subject distances become the near and far points of the depth of field, respectively. . 2. In a camera subject distance measuring device that measures a plurality of points on a photographic screen, a means for detecting the center, nearest, and farthest subject distance within the photographic screen among the plurality of measured subject distances; The first shooting mode focuses on the center of the shooting screen or the closest subject distance,
Alternatively, the second shooting mode includes means for determining the aperture value and focusing distance of the shooting lens so that the nearest and farthest subject distances become the near point and far point of the depth of field, respectively, and . A subject distance measuring device for a camera, comprising a switching means for switching between the first and second photographing modes.